What would you need to measure in a planetary nebula to determine how long ago its parent star died?
A) the mass of the white dwarf
B) the mass and radius of the white dwarf
C) the nebula's temperature and radius
D) the nebula's radius and expansion velocity
E) the composition of the gas in the nebula

Question

Quizplus · Accepted Answer

The nebula's radius and expansion velocity can be used to estimate the time since the parent star died by calculating how long it has taken for the nebula to expand to its current size.

What Would You Need to Measure in a Planetary Nebula